This is consistent with what the research has shown in other mammals - as I've read in the research papers. After a certain point - I forget exactly when - but perhaps around 14 months or so - I noticed that the additional choline provided by egg yolks no longer seemed to provide the same increase in waking energy and reduced sleep. He'd eat his egg yolk(s) and his nap schedule was no longer impacted. This has been the case for most of the last 6 months or so - but this week I noticed something unusual.
Early in life - the impact of the added choline on our son (who was exposed to about 3.5 grams of choline / day during pregnancy) was very clear and rapid; he didn't get tired during the normal times, and with two egg yolks would skip his naps entirely and stay wide awake and playful until a late bedtime (8 or 9pm if I remember correctly).
This week I realized that the additional choline received from the egg yolks does seem to still be having an impact on his sleep patterns. The past few weeks I've been giving him the occasional omelette which consists just of three egg yolks (no whites) - or about 350 mg of choline. When I do this there is no change in his daily sleep habits - he still sleeps his normal 2 to 3 hour long nap from about noon to 3pm, and goes to be around 7/8pm. This is, I think, why I thought the "Choline Effect" had worn off and was no longer effective.
But for most of the past few months our son has been a very regular 12 hour a night sleeper - if he goes to bed at 7pm, he wakes up at 7am. If he goes to sleep at 8pm, he wakes up at about 8am. But then I started giving him these 3-egg omelettes and suddenly he was waking up at 5:30am or 6am in the morning. I've now noticed this every time I give him the three egg omelette. It seems that the choline effect is delayed now that he's older - so that it hits him about 20 hours after he consumes the eggs and added choline. Interesting.
I've backed off on his three-egg breakfast omelettes now because I need the sleep - but I'll be trying some 3 egg-yolk omelettes at lunch and dinner and see what happens, and will report back.